With the touch screen products entering into people's lives, it is gradually found that when a touch screen is touched, false point reporting usually occurs or the touch screen may fail to recognize the touch, or touch reporting has generated even before a touch screen product is touched by a finger. Above problems are generally caused by interference of a common mode noise to the touch screen.
For example, a scanning channel of a current capacitive touch panel is usually divided into a driving channel and a sensing channel. A touch control chip transmits a driving signal to the driving channel and receives a sensing signal through the sensing channel. When a common mode noise is superimposed on the driving signal, the sensing signal received by the sensing channel will change. In the case, the touch control chip will receive a false sensing signal, so that inaccurate point reporting will occur. Therefore, in order to improve accuracy of touch reporting generated by the touch chip, it needs to reduce impact of a common mode noise, and before that, the common mode noise needs to be detected.